1. Field of the Disclosure The present disclosure relates to an electroluminescence device and a method of manufacturing the same, and more particularly, to a nanoparticle electroluminescence device having excellent light emission and an improved luminescence efficiency, and a method of manufacturing the same.
2. Description of the Related Art
Electroluminescence (EL) devices are devices which emit light by electrical excitation. For example, when electric energy is supplied to electrons in a low energy level and the electrons move to a higher energy level when the electric energy is cut off, the electrons return to the low energy level and light of predetermined wavelength may be generated. Organic EL devices are examples of EL devices and have a basic structure in which a thin organic emitting layer having a thickness of about 100-200 nm is interposed between an anode formed of indium tin oxide (ITO) as a transparent electrode, and a cathode such as a metal having a small work function, for example, Ca, Li, Al/Li, Mg/Ag, etc. In these organic EL devices, electroluminescence is produced by recombination of electrons and holes injected from both electrodes.
In the prior art, research for using luminescence particles, that is, nanoluminescence particles of nanometer dimensions as material for emitting layers, for these EL devices has been performed. Nanoparticles have an uncontinuous energy level, unlike bulk particles. Nanoparticles have different physical, chemical and photoelectron properties from those of bulk particles. In particular, it is known that nanoparticles can be used to form a material for an emitting layer (EML), because light having a variety of wavelengths, that is, light from a total visible area and a blue color to an ultraviolet-ray area can be easily produced due to an increase in an energy bandgap and a quantization effect as the size of the nanoparticles decreases.
It is known that if the size of fine silicon (Si) is of nanometer dimensions, luminescence in a visible light area can be obtained at room temperature. For example, luminescence from violet light in a blue color area can be observed from a thin film formed of Si nanoparticles having an average diameter of 3 nm. The result, which suggests direct transition in an Si crystal caused by a quantization size effect is known about. However, research for Si fine particles is still at an experimental stage, and development of an emitting layer (EML) material having a stronger luminescence strength that generates light having a short luminescence wavelength is further required so as to implement a device having new functions.
Japanese Patent No. 1997-181353 discloses a method of manufacturing Si fine particles and a luminescence device using an Si fine particle thin film. Here, the Si fine particles are manufactured by cooling Si in a vapor state using a solvent, and the luminescence device includes a thin film on which the Si fine particles are stacked. However, defects such as dangling bonds or vacancy etc. may exist on the surface of the Si fine particles. These defects may badly affect luminescence efficiency and luminescence characteristics of Si fine particles.